Rippe K, Jovin T M
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, FRG.
Biochemistry. 1989 Nov 28;28(24):9542-9. doi: 10.1021/bi00450a044.
Four 25-nt oligonucleotides consisting of sequences of dA and dT (D1-4) have been synthesized. As shown in a companion paper (Rippe et al., 1989), the two combinations D1.D3 and D2.D4 form normal antiparallel duplexes, whereas the pairs D1.D2 and D3.D4 constitute duplexes with the same sequences, but with the two strands parallel to each other. The activities of the following DNA processing enzymes and chemical reagents on the parallel stranded (ps) and antiparallel stranded (aps) duplexes were tested. (i) The restriction endonucleases DraI, SspI, and MseI do not cut the ps duplexes. (ii) DNase I and exonuclease III exhibit a much lower activity with the ps duplexes. (iii) The nuclease activities of S 1 nuclease, micrococcal nuclease (S 7), phage lambda 5'-exonuclease, and the 3'-5' nuclease activity of Escherichia coli DNA polymerase I and its large fragment are higher with the ps than with the aps substrates. (iv) Bal 31 nuclease and the chemical nuclease 1,10-phenanthroline-copper ion [(OP)2Cu+] degrade ps-DNA and aps-DNA at approximately the same rate but show preferred cutting sites only with the aps molecules. (v) The iron(II)-EDTA complex has equivalent nuclease activities with the ps and the aps molecules. (vi) The ps duplex is not a substrate for blunt-end ligation with phage T4 DNA ligase.
已合成了由dA和dT序列组成的4条25个核苷酸的寡核苷酸（D1 - 4）。如一篇配套论文（里普等人，1989年）所示，两种组合D1.D3和D2.D4形成正常的反平行双链体，而D1.D2和D3.D4对构成具有相同序列但两条链彼此平行的双链体。测试了以下DNA加工酶和化学试剂对平行链（ps）和反平行链（aps）双链体的活性。（i）限制性内切酶DraI、SspI和MseI不切割ps双链体。（ii）DNase I和核酸外切酶III对ps双链体的活性要低得多。（iii）S1核酸酶、微球菌核酸酶（S7）、噬菌体λ 5'-核酸外切酶以及大肠杆菌DNA聚合酶I及其大片段的3'-5'核酸酶活性对ps底物的活性高于对aps底物的活性。（iv）Bal 31核酸酶和化学核酸酶1,10 - 菲咯啉 - 铜离子[（OP）2Cu +]以大致相同的速率降解ps - DNA和aps - DNA，但仅对aps分子显示出优先切割位点。（v）铁（II） - EDTA络合物对ps和aps分子具有同等的核酸酶活性。（vi）ps双链体不是噬菌体T4 DNA连接酶平端连接的底物。
